River and Coastal Processes: Shaping the Earth's Surface

Work of Rivers

Rivers erode their beds, making them wider and deeper. Erosion is heightened during periods of high flow rate and increased water volume.

Flow

Flow is the volume of water transported per unit of time. The amount of material a river carries depends on its flow and speed. Materials can be transported as:

• Dissolved salts: Substances dissolved in the water.
• Suspended particles: Small particles traveling within the water.
• Saltating particles: Larger particles bouncing along the riverbed.
• Traction: The rolling or dragging of large particles along the riverbed.

Upper Course

With higher water speed, erosion creates a deeper V-shaped valley.

Middle Course

With reduced speed, materials are deposited at the bottom of the riverbed, and erosion continues along the margins.

Lower Course

The valley becomes much more open.

Subterranean Water

Aquifer

An aquifer is a porous underground rock layer that stores and transmits water.

Phreatic Level (Water Table)

The phreatic level is the highest level of water in an aquifer.

Well

A well is a borehole that reaches an aquifer.

Artesian Well

An artesian well is one where water flows to the surface naturally because the water table is at a height above the well opening.

Glaciers

A glacier is a large mass of ice that slowly melts on the surface. Glacier formation occurs through:

1. Compaction: Snow transforms into ice.
2. Melting and Refreezing: Snow melts, and the water refreezes in areas with temperatures below 0°C.

Types of glaciers:

1. Ice Caps: Examples include those in Greenland and Antarctica.
2. Alpine Glaciers: Found in high mountains, they have three distinct areas: the cirque, the tongue, and the terminal area.

Wind

Wind is the movement of air masses with different temperatures. Hot air rises because it is less dense than cold air, and cold air moves beneath the rising hot air. Wind carries small particles. When the wind stops, these particles settle through deposition.

Dunes

The continuous accumulation of sand can lead to dunes. Crescent-shaped dunes are called barchans. The side of the dune facing the wind is called the windward side, and the sheltered side is called the leeward side.

Loess

Loess deposits consist of smaller particles called silt.

Particle sizes (from largest to smallest): Gravel, sand, silt, and clay.

Sea

Waves

Waves are undulating movements produced by the contact between wind and the water's surface.

Tides

Tides are the rise and fall of sea level caused by the gravitational pull of the moon and the sun on Earth.

Currents

Currents are large masses of seawater moving through the oceans. They are produced by differences in temperature and wind.

These movements cause erosion, sedimentation, and transport phenomena in the sea, similar to those caused by moving water, wind, and glaciers. The primary causes of these movements are solar energy and gravity.